This study analyzed the relationship between urban CO2 emissions and economic growth applying the environmental Kuznets curve hypothesis. The objective of this study is to investigate how urban CO2 emissions and their composition have changed with urban economic growth, depending on city characteristics, using a dataset of metropolitan areas. We obtained data for 276 cities in 26 countries for the years 2000, 2005, and 2008. The dataset includes urban CO2 emissions, GDP, and population. Additionally, data regarding compact city variables are applied to determinants analysis using an econometric approach. The results demonstrate an inverted U-shape relationship between urban CO2 emissions and urban economic growth. Additionally, an inverted U-shape relationship is observed for the transport and residential & industry sectors. However, the turning points of each inverted U-shape curve varies. This result implies that we can better understand urban policies for reducing urban CO2 emissions by considering the characteristics of each sector.